Thermoelectric module and manufacturing method of thermoelectric module terminal

Abstract

A thermoelectric module includes: a lower substrate; an upper substrate disposed opposite the upper side of the lower substrate; a plurality of p-type and n-type thermoelectric elements disposed between the lower and upper substrates; first electrodes disposed on the lower surface of the lower substrate and the upper surface of the upper substrate and alternately connected to the p-type and n-type thermoelectric elements in series; and second electrodes disposed on the lower substrate and connected to the thermoelectric elements at the ends of the series circuit and to a terminal post having: a terminal post body formed of titanium; and a titanium passivation film covering the side surface of the terminal post body.

Description

Technical Field

[0001] This invention relates to thermoelectric modules and a method for manufacturing terminals for thermoelectric modules.

[0002] This application claims priority to JP Special Purpose No. 2019-189373, filed in Japan on October 16, 2019, the contents of which are incorporated herein by reference. Background Technology

[0003] Thermoelectric modules have been widely used up to date as circuit elements that absorb or generate heat through the Pelcher effect. As an example, as described in Patent Document 1 below, a thermoelectric module includes: p-type and n-type thermoelectric elements; a pair of electrodes connecting these thermoelectric elements; terminals for supplying current to the electrodes; and a housing covering the thermoelectric elements, electrodes, and terminals from the outside. The p-type and n-type thermoelectric elements are connected alternately and in series, with columnar terminals made of nickel provided at both ends of this series circuit. Current is supplied by setting one terminal as the positive electrode and the other terminal as the negative electrode. Thus, the Pelcher effect is generated in the thermoelectric elements, resulting in heat absorption at one electrode and heat generation at the other electrode.

[0004] Here, if the temperature control temperature of the thermoelectric element is lower than the dew point of the surrounding atmosphere, frost may form on the thermoelectric module. If frost forms, a phenomenon known as electrochemical migration will occur at the aforementioned terminals. Electrochemical migration refers to the phenomenon where the insulation between electrodes in an electrical circuit becomes substandard due to significant electrical, chemical, and thermal factors, causing the electrode metal to dissolve and be reduced as ions, thus leading to a short circuit. To avoid this electrochemical migration, a structure is considered that seals the outer casing relative to the outside and fills the interior of the casing with an inert gas.

[0005] Prior art literature

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2016-111326 Summary of the Invention

[0008] -The problem the invention aims to solve-

[0009] However, sealing the casing and filling it with inert gas, as described above, cannot be considered economical due to the increased manufacturing costs and time involved. Therefore, there is a growing demand for thermoelectric modules that can further suppress electrochemical migration while maintaining a simpler structure.

[0010] The present invention was made to solve the above-mentioned problems, and its object is to provide a thermoelectric module that can further suppress electrochemical migration based on a simple structure, and a method for manufacturing a terminal block for the thermoelectric module.

[0011] -Methods used to solve problems-

[0012] To address the aforementioned issues, the thermoelectric module of this invention comprises:

[0013] lower base plate;

[0014] The upper substrate is disposed opposite to the lower substrate above it;

[0015] Multiple p-type and n-type thermoelectric elements are respectively arranged between these lower substrates and upper substrates;

[0016] A first electrode is disposed on the upper surface of the lower substrate and the lower surface of the upper substrate, and is alternately and sequentially connected to the p-type and n-type thermoelectric elements, thereby forming a series circuit; and

[0017] The second electrode is disposed on the lower substrate and connects the thermoelectric element and the terminal at the end of the series circuit.

[0018] The terminal block has:

[0019] The terminal body is formed comprising titanium; and

[0020] A titanium passivation film is applied to cover the sides of the terminal block.

[0021] -Invention Effects-

[0022] According to the present invention, a thermoelectric module that can further suppress electrochemical migration based on a simple structure, and a method for manufacturing a terminal block for a thermoelectric module, are provided. Attached Figure Description

[0023] Figure 1 This is a cross-sectional view showing the structure of the optical module according to an embodiment of the present invention.

[0024] Figure 2 This is a cross-sectional view showing the structure of the thermoelectric module according to an embodiment of the present invention.

[0025] Figure 3 This is a perspective view showing the structure of the terminal block according to an embodiment of the present invention.

[0026] Figure 4 This is a flowchart illustrating the various steps of the manufacturing method of the terminal block according to the embodiments of the present invention.

[0027] Figure 5This is a perspective view showing the structure of the blank in the preparation step of the manufacturing method of the terminal block according to the embodiments of the present invention.

[0028] Figure 6 This is a perspective view showing the structure of the plated blank after the plating process is completed in the manufacturing method of the terminal block according to the embodiments of the present invention.

[0029] Figure 7 This is a perspective view showing the state after the cutting process is completed in the manufacturing method of the terminal block according to the embodiment of the present invention. Detailed Implementation

[0030] (Structure of an optical module)

[0031] The following is for reference Figures 1 to 7 The optical module 100 and the thermoelectric module 1 according to embodiments of the present invention will be described. The optical module 100 is used, for example, in optical communication. Figure 1 As shown, the optical module 100 includes a thermoelectric module 1, a light-emitting element 101, a heat sink 102, a first connector 103, a light-receiving element 104, a second connector 105, a temperature sensor 106, a metal plate 107, a lens 108, a lens holder 109, a wire 112, and a housing 113.

[0032] Furthermore, the optical module 100 includes an optical splitter 115, an optical ferrule 116, an optical fiber 117, and a sleeve 118.

[0033] Thermoelectric module 1 is a circuit element that absorbs or generates heat through the Pelcher effect. The detailed structure of thermoelectric module 1 will be described later.

[0034] Light-emitting element 101 emits light. Light-emitting element 101 may include, for example, a laser diode that emits laser light. Heat sink 102 supports light-emitting element 101. Heat sink 102 dissipates heat generated by light-emitting element 101. First connector 103 supports heat sink 102. Heat sink 102 is fixed to first connector 103.

[0035] The light-receiving element 104 detects the light generated from the light-emitting element 101. The light-receiving element 104 includes, for example, a photodiode. The second connector 105 supports the light-receiving element 104. The light-receiving element 104 is fixed to the second connector 105.

[0036] Temperature sensor 106 detects the temperature of metal plate 107. Temperature sensor 106 includes, for example, a thermistor.

[0037] The metal plate 107 supports the first connector 103, the second connector 105, and the temperature sensor 106. The first connector 103, the second connector 105, and the temperature sensor 106 are fixed to the metal plate 107 by welding.

[0038] Lens 108 focuses the light emitted from light-emitting element 101. Lens holder 109 supports lens 108.

[0039] The housing 113 houses the thermoelectric module 1, the light-emitting element 101, the heat sink 102, the first connector 103, the light-receiving element 104, the second connector 105, the temperature sensor 106, the metal plate 107, the lens 108, and the lens holder 109. An opening 114 is formed in the housing 113 for light emitted from the light-emitting element 101 to pass through.

[0040] A light splitter 115 is configured on the outside of the housing 113 to block the opening 114. The light splitter 115 allows light traveling in one direction to pass through and blocks light traveling in the opposite direction. Light emitted from the light-emitting element 101 and passing through the lens 108 passes through the opening 114 and enters the light splitter 115. The light incident on the light splitter 115 passes through it.

[0041] The optical ferrule 116 guides the light emitted from the optical splitter 115 to the optical fiber 117. The sleeve 118 supports the optical ferrule 116.

[0042] Next, the operation of the optical module 100 will be explained. The light emitted from the light-emitting element 101 is focused by the lens 108 and then enters the optical splitter 115 through the opening 114. After passing through the optical splitter 115, the light enters the end face of the optical fiber 117 through the optical ferrule 116.

[0043] Heat generated from the light-emitting element 101 is conducted to the metal plate 107 via the heat sink 102 and the first connector 103. A temperature sensor 106 detects the temperature of the metal plate 107. When the temperature sensor 106 detects that the temperature of the metal plate 107 has reached a predetermined given temperature, current is supplied to the thermoelectric module 1. The thermoelectric element 3 of the thermoelectric module 1 is energized, thereby the thermoelectric module 1 absorbs heat through the Pelche effect. Thus, the light-emitting element 101 is cooled. The temperature of the light-emitting element 101 is regulated by the thermoelectric module.

[0044] <Thermoelectric Module>

[0045] like Figure 2As shown, the thermoelectric module 1 has a pair of substrates 2 (upper substrate 21 and lower substrate 22), a plurality of thermoelectric elements 3 (p-type thermoelectric element 3P and n-type thermoelectric element 3N) disposed between these substrates 2, a first electrode 4A (upper electrode 41 and lower electrode 42) connecting these thermoelectric elements 3, a terminal 111 and a second electrode 4B.

[0046] The upper substrate 21 and the lower substrate 22 are formed as plates including an electrically insulating material. As an example, the upper substrate 21 and the lower substrate 22 are formed as ceramic. The upper substrate 21 is positioned opposite the lower substrate 22 and is spaced apart.

[0047] Multiple thermoelectric elements 3 are arranged spaced apart from each other between the upper substrate 21 and the lower substrate 22. In other words, thermoelectric elements 3 are disposed opposite each other on the upper surface of the lower substrate 22 and the lower surface of the upper substrate 21, separated by electrodes 4 described later. Depending on the polarity of the semiconductor contained in the thermoelectric element 3, the thermoelectric element 3 may include p-type thermoelectric elements 3P and n-type thermoelectric elements 3N. In this embodiment, these p-type thermoelectric elements 3P and n-type thermoelectric elements 3N are arranged alternately in cross-sectional view.

[0048] like Figure 2 As shown, an upper electrode 41 is provided on the upper end face of the p-type thermoelectric element 3P and the n-type thermoelectric element 3N, and a lower electrode 42 is provided on the lower end face. Both the upper electrode 41 and the lower electrode 42 are formed on the substrate 2 as wiring members including metal foil, etc. The p-type thermoelectric element 3P and the n-type thermoelectric element 3N adjacent to the p-type thermoelectric element 3P are connected to each other through the lower electrode 42. The n-type thermoelectric element 3N and the p-type thermoelectric element 3P adjacent to the n-type thermoelectric element 3N are connected to each other through the upper electrode 41. Thus, the p-type thermoelectric element 3P and the n-type thermoelectric element 3N are connected alternately in sequence to form a series circuit.

[0049] A terminal post 111 is erected on the upper surface of the lower substrate 22. The terminal post 111 is electrically connected to the thermoelectric element 3 located at the end of the aforementioned series circuit via a second electrode 4B provided on the upper surface of the lower substrate 22. A wire 112 for supplying current from the outside is connected to the upper end face of the terminal post 111. In other words, current is supplied to the thermoelectric element 3 via the wire 112 through the terminal post 111. Furthermore, in Figure 2 In the middle, only one terminal 111 is indicated. One terminal 111 is set as the positive terminal and one as the negative terminal, for a total of two.

[0050] <Terminal>

[0051] like Figure 3As shown, the terminal 111 has: a terminal body 5; an intermediate layer 6 respectively disposed on the two end faces in the vertical direction of the terminal body 5; a plating portion 7 disposed on the outer side of the intermediate layer 6; and a passivation film 5F (titanium passivation film) covering the side surface of the terminal body 5.

[0052] The terminal body 5 is a prismatic shape integrally formed from titanium. When titanium comes into contact with air, it immediately modifies, forming a passivation film 5F on its surface. In other words, the sides of the terminal body 5 are not subjected to any processing or treatment after manufacturing. The passivation film 5F is an oxide film formed on the surface of the titanium. Because the passivation film 5F does not dissolve even when exposed to solutions or acids, it protects the internal titanium (terminal body 5) and inhibits the progression of oxidation. Furthermore, the "sides" of the terminal body 5 refer to the four surfaces other than the surface that engages with the lower electrode 42 and the surface opposite to that engagement surface.

[0053] The intermediate layer 6 is a metal film provided to improve the penetration of the plating portion 7. Specifically, the intermediate layer 6 is preferably at least one selected from the group consisting of gold, palladium, platinum, and rhodium. Alternatively, a structure in which the plating portion 7 (described later) is directly provided to the terminal body 5 without providing the intermediate layer 6 can also be adopted.

[0054] The plating portion 7 has: an upper plating portion 71 (first plating portion) formed on the upper end side of the terminal body 5, i.e., the first surface; and a lower plating portion 72 (second plating portion) formed on the lower end side, i.e., the second surface. The upper plating portion 71 is a plating layer formed of gold. The lower plating portion 72 is a plating layer formed of an alloy of gold and tin. In addition, the intermediate layer 6 can be provided between the lower plating portion 72 and the terminal 111, and between the upper plating portion 71 and the terminal 111, at least one of them.

[0055] <Manufacturing Method of Terminals>

[0056] Next, refer to Figures 4-6 The manufacturing method of terminal 111 is described. For example... Figure 4 As shown, the manufacturing method includes a preparation step S1, an intermediate layer formation step S2, a plating process S3, and a cutting process S4.

[0057] In the preparation process S1, a sheet (bulk 8) formed of titanium is prepared. Figure 5The blank 8 has a pair of end faces in the thickness direction that are oriented in a direction that is separated from each other. More specifically, when the blank 8 extends into the XY plane, the thickness direction is the Z-axis direction in the XYZ coordinate system. In the intermediate layer forming process S2, the intermediate layer 6 is formed on one side (upper surface) and the other side (lower surface) of the blank 8 in the thickness direction. Alternatively, the subsequent plating process S3 can be performed without performing the intermediate layer forming process S2. In the plating process S3, the plating portion 7 is formed on the outer side of the intermediate layer 6. Specifically, an upper plating portion 71 based on gold is formed on the upper surface side, and a lower plating portion 72 based on an alloy of gold and tin is formed on the lower surface side. Thus, a plating blank 8G is obtained. Then, a cutting process is performed on the plating blank 8G. By cutting, the plating blank 8G is cut (cut) into a grid shape in the thickness direction. Thus, a plurality of terminals 111 are obtained. Figure 7 As described above, this completes all the processes involved in the manufacture of terminal 111.

[0058] <Effect>

[0059] Here, for example, consider the case where terminal 111 is formed of nickel. In this case, if the temperature control temperature based on thermoelectric element 3 is lower than the dew point of the surrounding atmosphere, frost may form on thermoelectric module 1. If frost forms, a phenomenon called electrochemical migration will occur at the aforementioned terminal 111. Electrochemical migration refers to the phenomenon where the insulation between electrodes in an electrical circuit becomes substandard due to important factors such as electrical, chemical, and thermal factors, causing the electrode metal to dissolve and be reduced as ions, resulting in a short circuit. If such a phenomenon occurs, it may hinder the stable operation of thermoelectric module 1. To avoid this electrochemical migration, for example, consider a structure in which the casing is sealed relative to the outside and the interior of the casing is filled with an inert gas.

[0060] However, sealing the casing and filling it with inert gas is not economical due to the increased manufacturing costs and time. Therefore, there is a growing demand for thermoelectric modules that can further suppress electrochemical migration while maintaining a simple structure.

[0061] Therefore, in this embodiment, the terminal 111 is formed of titanium. The terminal body 5 is formed of titanium, thereby naturally forming a passivation film 5F on its side. By forming this passivation film 5F, even in the event of frost formation as described above, modification or deterioration caused by moisture can be prevented. Furthermore, even if the passivation film 5F is scratched and the titanium is exposed, a new passivation film 5F can be formed immediately to cover the scratch. As a result, the environmental resistance of the terminal 111 can be improved.

[0062] Furthermore, in the above structure, an upper plating portion 71 based on gold is formed on the upper end face of the terminal block body 5, and a lower plating portion 72 based on an alloy of gold and tin is formed on the lower end face. This optimizes the insertion of the wire 112 relative to the upper plating portion 71. Moreover, compared to the lower plating portion 72, it improves the insertion of the wire 112 towards the lower electrode 42 based on soldering.

[0063] Furthermore, an intermediate layer 6 is provided between these upper plating portions 71 and lower plating portions 72 and the terminal block body 5. This further reduces the possibility of peeling or detachment of the upper plating portions 71 and lower plating portions 72.

[0064] Furthermore, according to the manufacturing method described above, after forming the intermediate layer 6 and the plating portion 7 on both sides of the blank 8 in the thickness direction, the plated blank 8G is cut, thereby enabling the efficient manufacturing of a large number of terminals 111 in a short time. This reduces labor time and costs.

[0065] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the specific structure is not limited to these embodiments, and design changes that do not depart from the spirit of the present invention are also included. For example, in the above embodiments, the case where the thermoelectric module 1 is used as an element of the optical module 100 has been described. However, the thermoelectric module 1 can also be applied to other mechanical devices different from the optical module 100.

[0066] Industrial availability

[0067] Based on the above disclosure, it is possible to provide a thermoelectric module that can further suppress electrochemical migration on the basis of a simple structure, and a method for manufacturing a terminal block for the thermoelectric module.

[0068] -Symbol Explanation-

[0069] 100... Optical module, 1... Thermoelectric module, 2... Substrate, 21... Upper substrate, 22... Lower substrate, 3... Thermoelectric element, 3P... p-type thermoelectric element, 3N... n-type thermoelectric element, 4... Electrode, 4A... First electrode, 4B... Second electrode, 41... Upper electrode, 42... Lower electrode, 5... Terminal body, 5F... Passivation film, 6... Intermediate layer, 7... Plating section, 71... Upper plating section (first plating section), 72... Lower plating section (second plating section) 8... blank, 8G... plated blank, 101... light-emitting element, 102... heat sink, 103... first connector, 104... light-receiving element, 105... second connector, 106... temperature sensor, 107... metal plate, 108... lens, 109... lens holder, 111... terminal, 112... wire, 113... housing, 114... opening, 115... light splitter, 116... light ring, 117... optical fiber, 118... sleeve.

Claims

1. A thermoelectric module, comprising: a lower substrate; an upper substrate disposed opposite an upper side of the lower substrate; a plurality of p-type and n-type thermoelectric elements disposed between the lower substrate and the upper substrate, respectively; a first electrode disposed on an upper surface of the lower substrate and a lower surface of the upper substrate, and alternately sequentially connecting the p-type and n-type thermoelectric elements, thereby forming a series circuit; and a second electrode disposed on the lower substrate and connecting a thermoelectric element at an end of the series circuit and a terminal, the terminal comprising: a terminal body formed to include titanium; and a titanium passivation film covering a side surface of the terminal body.

2. The thermoelectric module according to claim 1, wherein the terminal further comprises: a first plating portion disposed on a first surface of the terminal connected to the second electrode and formed to include an alloy of gold and tin; and a second plating portion disposed on a second surface of the terminal opposite the first surface and formed to include gold.

3. The thermoelectric module according to claim 2, wherein the terminal further comprises: an intermediate layer disposed between the second plating portion and the terminal and between the first plating portion and the terminal.

4. The thermoelectric module according to claim 3, wherein the intermediate layer is formed to include at least one selected from the group consisting of gold, palladium, platinum, and rhodium.

5. A method of manufacturing a terminal for a thermoelectric module, comprising: a step of preparing a plate-shaped blank formed to include titanium and having a pair of end surfaces facing directions of separation from each other in a thickness direction; a step of forming a gold-based plating treatment on one end surface in the thickness direction of the blank and a gold and tin alloy-based plating treatment on the other end surface in the thickness direction of the blank, thereby forming a plated blank; and a step of cutting the plated blank into a lattice shape from the thickness direction, thereby forming a plurality of terminals.

6. The method of manufacturing a terminal for a thermoelectric module according to claim 5, wherein in the step of forming the plated blank, a step of forming an intermediate layer on a single surface in the thickness direction of the blank is performed before the plating treatment.

7. The method of manufacturing a terminal for a thermoelectric module according to claim 5, wherein in the step of forming the plated blank, a step of forming an intermediate layer on both surfaces in the thickness direction of the blank is performed before the plating treatment. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Images